20112分子生物学试题 A

卷号：（A） （2011年12月） 绝密

湖北师范学院普通本科期末考试试卷

分子生物学

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王友如 20112

系部 生命科学学院 专业 生物技术

一、名词解释（翻译并简单解释，每小题 2分，共16分）

1.tRNAi 2.RNAi 3. intein 4. intron 5.coding region; 6.coding strand; 7. operon 8.operator;

二 、单项选择题(选择正确答案，每小题 1.5 分，共24 分)

9. Which enzyme does not play a role in DNA replication? ( )

(A) DNA polymerase (B) Helicase

(C) Single-stranded binding protein (D) Guanyl transferase 10. Splicing is the process that does which of the following? ( )

(A) Remove introns and conserve exons (B) Remove exons and conserve introns

(C) Remove mutated regions of primary transcript RNA

(D) Add multiple adenosine bases to the end of a primary RNA transcript 11. The 5' capping process creates what type of linkage? ( )

(A) 5'-3' (B) 3'-5' (C) 5'-5' (D) 3'-3'

12. Codons that code for the same amino acid are called: ( )

(A) Synonyms (B) Similar (C) Degenerates (D) Complements

13. Which vector would you choose to express a foreign gene in a plant? D

A a baculovirus vector. B a retroviral vector. C a Yep vector. D a T-DNA vector. 14. What signals the end of transcription? ( )

(A) Stop codon (B) Terminator (C) The end of the DNA chain (D) RNA polymerase runs out

15. What is the name of the molecule that is added to the 5' end of eukaryotic RNA transcripts? ( )

(A) ATP (B) SnRNP (C) GTP (D) Phosphate

16. According to the wobble hypothesis, a U in the 5' position of the anitcodon can pair with: ( )

(A) U or C (B) A or G (C) A, C, or G (D) Only A

17. Which two of the following statements about transcription factors are true? D

A the helix-turn-helix domain is a transcriptional activation domain. B dimerization of transcription factors occurs through the basic domain. C leucine zippers bind to DNA.

D it is often possible to get functional transcription factors when DNA binding domains and activation domains from separate transcription factors are fused together.

18. Which of the following is not characteristic of prokaryotic terminators? ( )

(A) Rho-independent terminators (B) Rho-dependent terminators (C) The TATA box (D) Hairpin loops

19. What is the enzyme responsible for stitching together Okazaki fragments? ( )

(A) Helicase (B) Single-stranded binding protein (C) Primase (D) Ligase

20. Denaturation of double stranded DNA involves. A preakage into short double-stranded fragments. B separation into single strands. C hydrolysis of the DNA backbone.

D cleavage of the bases from the sugar-phosphate backbone.

21. In prokaryotes, the lagging strand primers are removed by . . . A 3' to 5' exonuclease. B DNA ligase.

C DNA polymerase I. D DNA polymerase III.

22. Prokaryotic plasmids can replicate in yeast cells if they contain a cloned yeast. .

A ORC. B CDK. C ARS. D RNA.

23. Per nucleotide incorporated, the spontaneous mutation frequency in E. coli is . . .

A 1 in 106. B 1 in 108.

C 1 in 109. D 1 in 1010.

24 . Which two of the following statements about attenuation at the trp operon are true? A attenuation is rho-dependent.

B deletion of the attenuator sequence results in an increase in both basal and activated levels of transcription from the trp promoter.

C the attenuator lies upstream of the trp operator sequence.

D attenuation does not require tight coupling between transcription and translation.

E pausing of a ribosome at two tryptophan codons in the leader peptide when tryptophan is in short supply causes attenuation.

25. Which one of the following statements about catabolite-regulated operons is false? A cAMP receptor protein (CRP) and catabolite activator protein (CAP) are different names for the same protein.

B when glucose is present in the cell cAMP levels fall. C CRP binds to cAMP and as a result activates transcription. D CRP binds to DNA in the absence of cAMP.

E CRP can bend DNA, resulting in activation of transcription.

三 、填空题 (每空1分，共10分)

26. The simplest cloning vector at least contains and ori elements. 27. The diagram below shows two RNA molecules. Molecule I is processed

to give molecule II. Answer the following questions about these two molecules: Where does this conversion happen? ____________________________ What type of RNA molecule is molecule I? _________________________ What type of RNA molecule is molecule II? _________________________ Name the regions/structures indicated by the arrows: A = _________________ B = _______________

C = _________________ D = ______________ E = ________

四、简答题（回答要点,每小题4 分，共五小题，共20分）

28 When you study the DNA components of phage ΦΧ174, you get the results as follows: A，25%；T，33%；G，24%；C，18%. Question (1): Does your results abide by base pairing rules? Question (2): How do you explain your results?

29. DNA ligase plays important role in the process of DNA replication, but ligase does not function in the process of RNA synthesis. Could you explain it? 30 Do you think that rRNA and tRNA are more stable than mRNA? Why? 31. How does a coding region DNA sequence code different types of protein? 32. Could you list 4 kinds of RNA that have the ability to catalytic activity?

五、问答题（每小题10 分，共20分）。

33. Please tell us the types of RNA that you know, it would be better that you explain their function in living organisms. (10 points )

34. Take the case of arabinose operon, Could you explain what cis-acting element and trans-acting factor are, how do they interact with each other to regulate this operon? (10 points )

六、分析题（每小题10 分，共 10 分） 35. A scientist got a gal promoter mutant E.coli.which can not use galactose(半乳糖) in the medium, if he mutated the gene cya (gene of cAMP 环化酶) and crp (cAMP Acceptor Protein gene) were mutated into cya- and crp- respectively, the second mutated E.coli.restored its ability to use galactose. Could you explain the results by using your molecular biological knowledge?

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